This invention relates to a new material composition which provides low blow-off impulse in a high dose x-ray environment.
When launching a massive missile strike, the reentry vehicles are accompanied by decoys, the purpose of which is to saturate the enemy defenses. Advanced reentry vehicle decoys are designed to produce radar signatures that cannot be distinguished from the signatures of the accompanying reentry vehicles. The reentry vehicle features that are used as discriminants are: (1) deviations in trajectory, (2) the dynamic radar cross section of the body, and (3) the radar cross section of the wake. It is important that all of these features be simulated by the decoy.
The likely defense against a cloud of incoming reentry vehicles and decoys would be a nuclear attack, ridding the cloud of some objects and producing a discriminating response between reentry vehicles and decoys. The defense could then zero in on and intercept only the reentry vehicles and avoid saturation.
All of the nuclear environments (photons, neutrons, blast, thermal, etc.) pose a threat at some altitude for either the active or passive body decoy concepts. The photon environment in the X radiation band poses a severe exo-atmospheric threat to both decoy concepts because it produces an external impulsive load on the decoy body. The external impulse can cause changes in the decoy motion, or actually damage the decoy, to the extent that it can be distinguished from the reentry vehicle. It is vital, therefore, to minimize the impulsive load.
The external impulsive load produces two effects. First, coning results because the decoy center-of-mass varies with exposure angle and external material distribution. Excessive coning can be seen in the decoy dynamics radar cross section which distinguishes it from the reentry vehicle. Excessive coning may also increase aerodynamic drag, changing the decoy trajectory and degrading metric simulation.
Second, the impulse load can induce dynamic response of the decoy, causing damage or failure of the structure and nose tips. Constraints placed on the decoy weight and reentry vehicle simulation requirements make it particularly difficult to strengthen the structure and nose tip sufficiently without compromising other performance factors. A reduction in the impulse load, therefore, can be of significant benefit to the overall system performance.
Impulse is produced by "cold" X-rays in the outermost decoy material. It is feasible to reduce the impulse load by applying a thin coating of low impulse material over the entire decoy. Besides generating a low X-ray impulse, the coating must also satisfy a number of other requirements to be consistent with the required decoy performance. These requirements are summarized as follows: